Money doesn't buy happiness, but it does buy options.
Most of the folks I know from my generation tend to spend almost all of their disposable income as soon as they obtain it. I have tried to explain to them that by doing so, they are selling their own freedom. You are forever at the yoke of he who employs you if you are living from paycheck to paycheck.
For the first three years of my career, I scrimped on almost all expenditures in order to accumulate a savings allowing me to be out of work for a period of at least one full year. I call it the FYF (the Fuck You Fund). I wouldn't trade it for anything but a true emergency.
Studies [0] have shown that, in essence, money and happiness correlate up to about $75k/year for a U.S. family of four. Above that level, money might open up options, but it doesn't seem to increase happiness as a whole. As others have noted, you can have a lot of financial freedom well below the million dollar mark, or be financially burdened above it.
It should come as no surprise that some people have come to that realization, and decided to simply meet the threshold, life a financially stable lifestyle at that level, and invest the rest of their energy in enjoying life.
[0] http://www.inc.com/news/articles/2010/09/study-says-$75,000-... describes one such study